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Re: questions about element declarations



Lee wrote:
>If scoping rules were introduced, could + and - be eliminated?

I  think the real question is "Would the scoping rules be any easier for
users to understand than the rules for inclusions?". I doubt it somehow.

>What is the expressive loss in elmiminating "&"?

If you have an & group with more that 3 options the number of expansions you
have to do makes the DTD unreadable/incomprehensible. If you use repeatable
OR groups instead you cannot ensure that only one occurrence of each element
occurs. Forcing people to enter things in a fixed sequence is the only real
alternative, and this constrains users to thinking in the same sequence as
the DTD writer, which can put them off using the DTD. I know & is hard on
the parser writers, but without user-friendly logically controlled input
there is no need for logically controlled output.

----
Martin Bryan, The SGML Centre, Churchdown, Glos. GL3 2PU, UK 
Phone/Fax: +44 1452 714029   WWW home page: http://www.u-net.com/~sgml/